Noise reduction is the process of removing noise from a signal. Noise may be any undesirable sound that is present in the signal, such as background noise present during speech. Generally, noise reduction includes noise estimation techniques to assist with identifying noise within a signal. All recording devices, both analog and digital, have traits which make them susceptible to noise. Noise can be random or white noise with no coherence, or coherent noise introduced by the device's mechanism or processing, or any other undesirable sound. Techniques for the reduction of background noise are used in many speech communication systems and electronic devices. Communication devices (e.g., smartphones, tablet computing devices, webcams, etc.) and hearing aids may utilize techniques to enhance the speech quality in adverse environments, or generally, in environments that include noise.